COMPOSITION OF THE PURE CHLORIDE OF SODIUM. Atoms. Eq. wt. Per cent. Ure. Longchamps. Sodium 1 23 39·3 39·98 39·767 Chlorine 1 35·5 60·7 60·02 60·233 — ———— —————— —————— ——————— 2 58·5 100·0 100·00 100·000 MM. St. Claire Deville and Fouqué have shown that common salt can be resolved into its elements by the action of hot steam alone, which Lussa and other chemists had thought impossible. Prof. Meyer, of Berne, has lately demonstrated by experiments on chlorine gas, that the assumption of its elementary character is an error, and that it is nothing more or less than the oxide of a metal which he calls _murium_. This discovery opens up an interesting question for physiological chemists to investigate; for if he is correct, chlorine is not an element, but is simply the oxide of a metal. CHAPTER IV. GEOGRAPHICAL DISTRIBUTION. Salt, fortunately for us, is a commodity remarkably easy to obtain; almost everyone knows it is in great abundance in the ocean,[30] and there are inexhaustible supplies of it in the earth; it is also present in some rivers, and in no inconsiderable quantity. Mr. John Ashley, in the _Quarterly Journal of the Chemical Society_, in his “Analysis of Thames Water,” tells us the exact amount: COMPOSITION OF THAMES WATER AT LONDON BRIDGE IN GRAINS PER GALLON OF 70,000 GRAINS. Carbonate of Lime 8·1165 Chloride of Calcium 6·9741 Chloride of Magnesium ·0798 Chloride of Sodium (salt) 2·3723 Sulphate of Soda 3·1052 Sulphate of Potash ·2695 Silica ·1239 Insoluble Organic Matter 4·6592 Soluble Organic Matter 2·3380 —————— 28·0385 We may account for this great proportion of salts by the fact that the Thames collects its water from the drainage of comparatively soft and soluble rocks; we should also remember the vast amount of refuse organic and inorganic matter which is being continually thrown into this river; and we must also call to mind that it is nothing more or less than the main sewer which receives the ordure of the modern Babylon.[31] We may naturally suppose that in those rivers which flow through sparsely inhabited countries, where there is little or no traffic, the amount of saline matter would be next to nothing, and probably not a trace would be discovered. In a river like the Thames, owing to the vast quantity of its shipping, the great percentage which Mr. John Ashley has given us need not afford the least surprise. Sea-water is deficient in its proper proportion of salt at the mouths of great rivers, where the volume of fresh water displaces that which properly belongs to the sea, and therefore a river does not obtain much saline matter from that source.